Utilization of Cogon Grass (Imperata cylindrica) in the Removal of Cyanide in Soil

Abstract

INTRODUCTION

Philippines have rich deposits of different minerals. This results to rampant mining industry operation in the different regions particularly in the province of Compostela Valley wherein ten out of eleven municipalities have gold deposits. With this, as means of finding the minerals from the ore, small-scale miners utilize cyanide leaching to extract gold from ores. Without proper waste disposal of this hazardous chemical, significant destruction the cyanide brought to the environment cannot be repaid. This study aims to remove waste cyanide from the contaminated soil and restore it using Cogon grass (Imperata cylindrica).

METHODS

Soil titration on the presumed contaminated soil was done to determine the strength of the cyanide if present. One and a half kilogram of Cogon grass was harvested and homogenized in the area enough to be utilized for 3 replicates with one-half kilogram in each replicate and another one-half kilogram sample from Cyanide-free soil for control ready for lab testing. Using Kjehldahl Method, percentage protein of the plant samples was measured. The results were then compared between the plant samples that were exposed to cyanide-contaminated soil and the control.

RESULTS

As reflected in the results, the soil titration exhibits a positive result that cyanide is present in the soil having a mean strength of 0.467 ppm. Furthermore, a significant difference in the means of the percentage of protein was found between the two plant samples. A 4.22% protein from the plant that was exposed to cyanide-contaminated soil has a notable contrast from 1.81% protein from the plant in the cyanide-free soil. T-test for independent samples resulted to a p-value of 0.004 and df of 2 at α-level 0.05 that leads to a decision to reject H0.

DISCUSSIONS

The increase in % protein denotes that the Cogon grass has managed to absorb the cyanide from the soil and use it for the plant's growth and at the same time restores the soil in its natural healthy state. Plant utilization of cyanide as a supplemental source of nitrogen has been a topic in recent scientific interest. Ebbs, S., et al., (2010), asserted that plants exposed to cyanide are healthier than those that have artificial nitrogen fertilizers. Through nitrogen assimilation in plants, nitrogen was transformed to amino acids useful in the production of proteins. Sorghum (Sorghum bicolor) and Willow (Salix viminalis,Salix viminalis x schwerinii) tree testifies that plants exposed to cyanide-contaminated soil become healthier.